One- Extra Rage can be applied to EITHER Barbarian Rage OR FB's Frenzy, not both. From the looks of it, it was taken long before the first FB level, therefore it must have been applied to the Barbarian's Rage.
Two- You can't IHS Frenzy. Frenzy demands that you attack your enemy (or ally, as the case may be) to the best of your ability, and using your standard action (IHS) to end a +6 (or +10) untyped Strength buff is basically the exact opposite of that.